Heather wrote:

A little trick told to me by someone who installed ponds as a business was
to have some pea gravel handy when using "Great Stuff" and cover it with the
pea gravel where it shows. Worth a try.

Now, that's a neat idea (ouch, didn't intend the pun).

I've had "Great Stuff" continue expanding for several hours when
applied at lower temperatures. That can be annoying. Use at warmer
temperatures, if you can, so you know what the results will be a bit
sooner.